By Matt Harrington, BCBA · Behaviorist Book Club · Research-backed answers for behavior analysts
The Picture Exchange Communication System is a structured, phase-based approach to teaching functional communication using picture card exchanges. It begins by training the learner to physically give a picture of a desired item to a communication partner in exchange for that item — establishing the mand as the first communicative behavior. This approach bypasses the need for eye contact or verbal imitation, making it accessible to learners who have not acquired communication through other means. PECS has a substantial evidence base, particularly for teaching requesting skills to young children with ASD who lack functional speech.
AAC selection should follow a feature-matching process that evaluates learner characteristics — motor access, cognitive profile, sensory preferences, current communicative functions — against the characteristics of candidate systems. Communication partner capacity, available resources, and the learning trajectory the system supports are also evaluated. No single modality is universally superior; PECS may be optimal for some learners while an SGD or app-based system better serves others. BCBAs should conduct or contribute to this assessment collaboratively with SLPs, who bring complementary expertise in language and device evaluation.
AAC and FBA are directly linked for learners whose problem behavior serves communicative functions. If the FBA indicates that problem behavior is maintained by access to preferred items, escape from demands, or attention, the AAC system must include vocabulary that allows those functions to be expressed. Functional communication training teaches an AAC-based communicative response that produces the same reinforcer as the problem behavior — replacing the behavioral function without eliminating the reinforcement. AAC vocabulary selected without reference to FBA results may fail to address the communicative functions driving problem behavior.
Research on PECS has demonstrated effectiveness for teaching requesting skills to children with ASD, with many studies showing rapid acquisition of picture exchanges and transfer to functional communication contexts. Some studies have also reported increases in speech production in PECS users, though PECS does not directly target speech and the mechanism for this effect is not fully established. The evidence base is stronger for the early phases of PECS (requesting) than for later phases targeting sentence structure and commenting. As with all AAC research, generalization to natural environments and maintenance over time require explicit programming.
Speech-generating devices (SGDs) are dedicated hardware systems designed specifically for AAC use. They are typically more durable, have longer battery life, and offer specialized access options for individuals with motor differences. App-based AAC systems run on general-purpose tablets or smartphones and are substantially less expensive, but may be more distracting, less durable, and have fewer access customization options. The behavioral mechanism — producing speech output in response to symbol selection — is similar across both. The choice between them often involves weighing cost and accessibility against durability and specialized access needs.
BCBAs operating within scope of practice in AAC typically focus on the behavioral acquisition procedures — the training protocols for teaching symbol selection, exchange, and communicative requesting — and on functional communication training that links AAC to the communicative functions identified in FBA. Device selection, vocabulary organization, symbol type, and access method evaluation are primarily within SLP scope of practice. BCBAs who conduct comprehensive AAC assessments or make device recommendations without adequate training and SLP collaboration may be operating beyond Code 1.06 (Maintaining Competence). Collaborative service delivery is the ethical and effective model.
PECS directly trains the mand — behavior that specifies its own reinforcement — from Phase 1 onward. The picture exchange is a mand: the learner exchanges a symbol for a specific item, and the reinforcer is the item itself. This distinguishes PECS from communication training that begins with labeling or tacting, which produces social reinforcement rather than direct access to a desired outcome. Mand training is prioritized in verbal behavior approaches because it produces the strongest, most durable communicative behavior — maintained by direct access to reinforcement rather than by socially mediated attention alone.
Communication partner training is essential for AAC outcomes and is frequently underemphasized in implementation. If communication partners — parents, teachers, therapists — do not respond consistently and correctly to AAC-based communicative attempts, the reinforcement contingencies that maintain communicative behavior are disrupted. Partners must also be trained to model AAC use, to wait for and honor communicative attempts, and to resist the temptation to prompt excessive responding. Partner training using behavioral skills training procedures — not just information transfer — produces the reliable, consistent partner behavior that AAC acquisition requires.
Family preference is clinically important data that should be taken seriously. When families prefer a different AAC approach than the assessment team recommends, the appropriate response is collaborative exploration — understanding the basis for the preference, sharing the evidentiary rationale for the clinical recommendation, and identifying whether a trial of the family-preferred approach can be conducted with fidelity and data collection. Family buy-in and consistent home implementation are critical for AAC generalization, and a technically superior system implemented inconsistently produces worse outcomes than a less optimal system implemented with fidelity and enthusiasm.
Multimodal communication — the use of multiple communicative modalities including gesture, vocalization, picture exchange, and SGD — reflects how most people naturally communicate. AAC planning should not artificially restrict the modalities a learner uses; adding a high-tech AAC system does not eliminate existing communicative behaviors including vocalization, pointing, or facial expression. BCBAs should assess the full communicative repertoire, support the expansion of all functional modalities, and avoid the misconception that introducing AAC will discourage speech development. Research does not support the concern that AAC reduces speech; in many cases, providing a reliable communicative modality is associated with increased vocalization.
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All behavior-analytic intervention is individualized. The information on this page is for educational purposes and does not constitute clinical advice. Treatment decisions should be informed by the best available published research, individualized assessment, and obtained with the informed consent of the client or their legal guardian. Behavior analysts are responsible for practicing within the boundaries of their competence and adhering to the BACB Ethics Code for Behavior Analysts.